Like USAFRet & Dunlop 0078 said; you can install windows using the boot disk (DVD or USB) and "activate windows later".
Then once u reach the system, start windows activation and try ur key. If it refuses to activate with it (and it pretty much will), then ...
Choose "phone activation" > copy the ID they give you and the toll-free number and call on skype > it will ask u to enter the ID we copied earlier, then it will ask about the number of machines it was activated on, then it will work.